As competition in the field of electric appliances has become increasingly fierce over recent years, more demanding technical requirements are being posed on products. For example, products are now required to be energy saving and environmentally friendly, and have a high degree of controllable intelligence, a short development period, and low noise. Electric motors, as the core part, have undoubtedly become a key part to solving the above-mentioned technical problems. Motors in conventional household central air conditioners are typically single phase permanent-split capacitor AC motors (PSC). However, single phase AC motors have low efficiency, consume more energy, have high noise, and have a low degree of controllable intelligence.
As a result of advances in motor technologies, permanent magnet (PM) synchronous motors have been developed. PM synchronous motors typically have a motor controller to electronically commutate current. As a result, PM synchronous motors are also referred to as electronically commutated (ECM) motors. PM synchronous motors are characterized in that they are energy saving and environmentally friendly, they have relatively high reliability and controllability, generate low noise, are easily made more intelligent, and can address the drawbacks of single phase AC motors. Therefore, the single phase AC motors in conventional household central air conditioners are gradually being replaced by PM synchronous motors. However, circuit ports are quite different for single phase AC motors and PM synchronous motors, which creates a problem because it is difficult for one motor to have two different circuit ports. When a conventional PM synchronous motor is used to replace the single phase AC motor in an existing household central air conditioner, it is necessary to replace the circuit port of the motor, change the motor circuit, etc., making the replacement inconvenient and costly.
In view of the foregoing drawbacks, ECM motors have been developed to directly replace the original PSC motors without the need to change the circuit structure of the original application systems of the PSC motors, e.g., the HVAC control system. The installation and troubleshooting of ECM motors in HVAC systems is simple, and the development cost associated with an ECM motor is lower than that of a PSC motor.
However, current ECM motors used to replace single phase AC motors still have numerous problems. For example, ECM motors have single functions and cannot be used under different circumstances. In addition, with an ECM motor driven by a THERMOSTAT, as shown in FIG. 1, the output ports W1, W2, Y1, Y2, and G of the THERMOSTAT output 24 V AC signals to the five tap lines T1, T2, T3, T4 and T5 of the ECM motor while the HVAC system that originally included the PSC fan motor outputs 115 V AC or 230 V AC signals. The two outputs are not compatible.